The U.S. Coast Guard cutter Mackinaw did exactly that when the icebreaking buoy-tender sailed down Lake Huron accompanying the cutter Biscayne Bay to a Detroit shipyard.

The Biscayne Bay, home-ported in St. Ignace, developed an engine problem that needed repair so the Mac hiked along to be ready in case the situation developed to the point that the Biscayne Bay lost power and needed immediate assistance, if not moral support.

If that should happen, what better vessel to have nearby than the Mackinaw?

Estimates are that the work on the Biscayne Bay’s engine should take about 10 days, when it would be ready to return to the Straits of Mackinac for duty breaking ice that is expected to form within the next two weeks.

The Mackinaw spent Thursday in the river north of Lake St. Clair, always a trouble spot for ice jams. The reconnaissance will likely prove invaluable later in the spring when ships resume moving commerce downbound through the Soo Locks.

The Soo Locks closed at midnight Tuesday, hours after the season’s final vessel, the 767-foot Cason J. Callaway, locked through the Poe Lock just after 6 p.m. downbound with 25,000 tons of taconite pellets.

In a news release, the U.S. Army Corps of Engineers Detroit District office said that district personnel will perform a 5-year periodic inspection of the MacArthur Lock, while work crews repair watertight doors and miter gates, and install a new air bubbler ice suppression system on the MacArthur Lock gates.

Concrete upgrades and installation of gate fenders are also planned in the MacArthur Lock. Piping will be installed in the Poe Lock for a new hydraulic system to operate the gates, booms and valves.

Built in 1968, the Poe is 1,200 feet long. The MacArthur was built in 1943 and is 800 feet long. Once winter maintenance is complete, the locks will reopen in March.

During the 2012 navigation season, 4,086 cargo vessels passed through the Soo Locks carrying about 75 million tons of iron ore, coal, grain and other commodities. In addition to cargo vessels, a total of 3,278 tour boats, private boats and other recreational vessels used the locks this past year.